纳米NiFe_2O_4磁性颗粒的制备及表征

Preparation and Characterization of Magnetic NiFe_2O_4 Nanocrystals

以硝酸铁和硝酸镍为原料,尿素为沉淀剂,在水热温度180℃和水热时间12 h合成了纳米NiFe2O4磁性颗粒,并利用X射线衍射仪(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)和振动样品磁场计(VSM)等分析方法对样品进行了表征.结果表明:水热法所得纳米NiFe2O4颗粒为尖晶石结构,粒度分布均匀,粒径约为20 nm,具有明显的超顺磁性,饱和磁化强度为14.39 emu/g.

Nanocrystalline NiFe2O4 magnetic powder was prepared by a hydrothermal method from Ni and Fe nitrates and urea as precipitate at 180 C for 12 h. The NiFe2O4 magnetic powder samples were characterized by X-ray diffraction （XRD）, transmission electron microscopy （TEM）, scanning electron microscopy （SEM）, and vibrating sample magnetometer （VSM）. SEM and TEM indicated that the particles were spherical sizes in the range 20 nm. VSM results show that the sample exhibits superparamagnetic effect and its maximum magnetization is 14.39 emu/g. In addition, a possible mechanism was proposed for the formation of NiFe2O4 nanocrystals.